Field of the Invention
The present invention relates to an X-ray topography apparatus that uses X-rays to form a two-dimensional image in correspondence with a crystal defect structure present in a single crystal sample.
Description of the Related Art
There is a known conventional X-ray topography apparatus disclosed, for example, in Patent Citation 1 (Japanese Patent Laid-Open Publication H08-124983). Patent Citation 1 discloses that a single and individual X-ray topographic image is captured. Patent Citation 1, however, does not disclose that a plurality of X-ray topographic images are acquired from a single sample.
Patent Citation 2 (Japanese Patent Laid-Open Publication 2006-284210) describes that a plurality of section topographic images (that is, two-dimensional cross-sectional images) are acquired by using X-rays and then caused to undergo multiple exposure. Patent Citation 2, however, provides no detailed description about the multiple exposure. According to typical interpretation, the multiple exposure is believed to mean exposure of a plurality of images superimposed on a single two-dimensional detector by using a large amount of step movement of the sample.
Patent Citation 3 (WO2008/052287A1) discloses that an X-ray source as small as 10 to 50 μm is used to output X-rays, that the width of the X-rays is limited with a slit, and that a sample is moved stepwise for acquisition of a plurality of diffraction images. Patent Citation 3, however, does not mention the intensity of the X-rays with which the sample is irradiated. When the X-ray source is small and the width of the X-rays is limited with a slit, the intensity of the X-rays that reach the sample is significantly attenuated, which means that the sample needs to undergo very long exposure, for example, for several hours to ten hours in order to provide a single desired X-ray image. No one has therefore considered acquisition of a large number of X-ray images or as many as several hundreds of X-ray images.
Non-Patent Citation 1 (http://cheiron2010.Spring8.or.Jp/text/bl/11_BL19B2.pdf, (file stamp date: 30 Sep. 2010), “beam line BL19B2 at Spring-8, synchrotron radiation facility”) discloses that a sample is moved stepwise with respect to synchrotron radiation for acquisition of section topographs of the sample irradiated with the synchrotron radiation in each step position and that the section topographs are superimposed on each other to provide a 3D (three-dimensional) image. Synchrotron radiation, which inherently contains high-intensity X-rays, allows acquisition of a plurality of section topographs in a relatively short period. The period required to acquire a plurality of section topographic images can therefore be greatly shortened. It is, however, impossible to use a synchrotron radiation facility in typical corporate research or manufacturing situations.
Non-Patent Citation 1 does not mention at all use of a laboratory-level X-ray source. Since a laboratory-level X-ray source outputs low-intensity X-rays, acquisition of a plurality of section topographs within a practically acceptable period of time by using the X-ray source is not worth consideration.
Non-Patent Citation 2 is the “Report on current status of X-ray topography research group” (Spring-8 User's Information/Vol. 13 No. 1 Jan. 2008/Research Group Report Spring-8 Users Society//Faculty of Science, University of Toyama, Satoshi IIDA, Graduate School of Engineering, Osaka University, Takayoshi SHIMURA, Japan Synchrotron Radiation Research Institute, Industrial Application Division, Kentaro KAJIWARA). Non-Patent Citation 2 discloses that a sample is scanned with synchrotron radiation and cross-sectional images of several portions of the sample irradiated with the synchrotron radiation are captured, and that the images are superimposed on each other in a computer for estimation of a three-dimensional distribution of in-crystal lattice distortion. Non-Patent Citation 2 does not describe at all use of a laboratory-level X-ray source, too. Since a laboratory-level X-ray source outputs low-intensity X-rays, acquisition of a plurality of section topographic images within a practically acceptable period of time by using the X-ray source is not worth consideration.
Patent Citation 4 (Japanese Patent Laid-Open Publication 2007-240510) discloses an X-ray topography apparatus in which a zone plate or any other X-ray collection means is used to collect X-rays and a sample is irradiated with the collected X-rays. Patent Citation 4 does not mention technologies for outputting X-rays from a minute focal spot, converting X-rays into monochromatic X-rays, collimating X-rays into a collimated beam, or increasing the intensity of X-rays. The apparatus described in Patent Citation 4 cannot therefore acquire a large number of section topographic images in a short period.